1. Field of the Invention
The invention relates to a steering apparatus for a vehicle.
2. Description of the Related Art
A tilt mechanism that changes a tilt angle of a steering column based on the posture and physique of a driver is described in, for example, Japanese Patent Application Publication No. 2002-2502 (JP-A-2002-2502), Japanese Patent Application Publication No. 2005-8022 (JP-A-2005-8022), and Japanese Patent Application Publication No. 2006-21569 (JP-A-2006-21569). A supporting structure in which such tilt mechanism is included and a steering column is fitted to a vehicle body is described in, for example, Japanese Patent Application Publication No. 2002-370653 (JP-A-2002-370653). In the supporting structure described in JP-A-2002-370653, a vehicle body-side bracket and a column-side bracket are fastened to each other by swaging a pivoted member, which is used as the shaft axis when the steering column is tilted, using a pin.
Japanese Examined Utility Model Registration Application Publication No. 04-34137 (JP-UM-B-04-34137) describes a tilt steering apparatus provided with a buffer member that minimizes vibration and noise caused by a contact between a movable bracket, which supports a steering column, and a restriction member due to a spring force when the steering column is flipped up.
Japanese Patent Application Publication No. 2000-62624 (JP-A-2000-62624) describes a steering apparatus that includes a steering column support portion with enhanced rigidity. Such high rigidity of the steering column support portion is achieved by providing a column-side bracket having an elaborated shape.
There is a so-called electric power steering apparatus that generates assist torque using a motor fitted to a column shaft portion and a speed reducer during a steering operation. The electric power steering apparatus detects the information on a steering operation performed by a driver and generates assist torque that proceeds in the direction in which a steering wheel is turned by the driver, thereby alleviating the driver's burden of turning the steering wheel.
However, when a shaft that is housed in a steering gear cannot be moved any more, for example, when a tire contacts a curbstone or when a steering wheel is turned to the fullest extent, if a force to turn the steering wheel is further applied by the driver, assist torque is applied to a column shaft. In this case, because the column shaft cannot rotate any more, a reaction force due to a drive power generated by the motor is applied to a securing portion that secures a bracket which supports the steering column to a vehicle body.
Therefore, a bracket needs to be designed with the strength thereof taken into account so that the bracket is reliably secured to the vehicle body even if such reaction force is applied to the securing portion. Especially when a bracket is used to support a steering column provided with a tilt mechanism, the bracket needs to be designed in such a manner that sufficiently high strength is ensured despite provision of the tilt mechanism. This causes an increase in the size of the bracket.